The present invention relates to counting systems which compile a total of the number of objects which have passed a reference point on a line of flow, typically a production line, for example, a canned beverage line. Such systems utilize sensing devices responsive to objects passing the reference point.
Certain systems in current use utilize a single sensor and amplifier along with a digital up-counter. In their simplest form these systems may count falsely; they increment the count whenever an object passes in either a forward or reverse direction, and also upon vibration and other erratic motions of the items to be counted.
Systems proposed to remedy these problems have used two sensors, the first positioned a short distance upstream from the second. These systems compare the sequence of the signals from the sensors, making a determination as to the direction of flow of the objects, and may count up only when a forward direction of flow has been determined. One known system utilizes an up-down counter along with a digital clock to trigger the logic circuitry, allowing the system to count both up and down. However, since typical production lines do not always flow smoothly, false counts may result from vibrations, reversals, and other erratic motions.